Apparatus for determining horizon productivity of wells



w. s. SEASE ,20

APPARATUS FOR DETERMINING HORIZON PRODUCTIVITY 0F WELLS May 28, 1940.

Filed May 25. 1938 INVENTOR W/'// J. Sease /dial ATTORN EY Patented May28, 1940 PATENT OFFICE APPARATUS FOR DETERMINING HORIZON PRODUCTIVITY OFWELLS Will S. Sease, Tulsa, Okla., assignor to Stanolind Oil and GasCompany, Tulsa, Okla., a corporation of Delaware Application May 25,1938, Serial No. 209,928

Claims.

This invention relates to apparatus for determining the flow of fluidsfrom various horizons in deep wells such as oil, gas or water wells, andI more particularly to apparatus for the determi- 5 nation of the rateof fluid flow in such wells at various levels therein.

Itis well-known that oil, gas or water wells may traverse severalfluid-bearing strata at different levels, and that a number of suchstrata may be simultaneously supplying fluids such as oil,'natural gasor water to the wells. A knowledge of the volume of fluid flowing intothe well from each of the various strata is very desirable in order thatthe well may be properly operated.

Although this knowledge is particularly important for wells which arebeing produced under reservoir pressure, it is also desirable in wellsequipped with the gas lift or having flow valves offset from the tubing.

It is an object of my invention to provide apparatus for determining thehorizon productivity in wells which is rapid and does not require theuse of packers or similar devices. Another object is to provide a simpleapparatus capable of 25 rapid use for locating the producing horizons ina producing well. Still another object is to provide apparatus forelectrically transmitting an indication of the velocity of the fluidrising in a producing well at various levels to the top of the 30 well.A further object is to provide a simple and rugged flowmeter adapted tobe lowered into a deep well. Further objects will be apparent from thefollowing detailed description read in conjunction with the drawing inwhich:

Figure 1 shows schematically a form of apparatus in accordance with myinvention;

Figure 2 is a vertical section of a preferred embodiment of apparatus inaccordance with my invention;

Figure 3 is a horizontal section taken along line v3-3 of Figure 2;

Figure 4 is a horizontal. section taken along line 44 of Figure 2; 45Figure 5 is an horizontal section taken along line 5-5 of Figure 2;

Figures 6 and 7 are schematic diagrams illustrating the principle usedin the apparatus of Figure 2.

In one of its broad aspects my invention comprises apparatus for thedetermination of the productivities or rates of flow of fluid from thevarious producing strata of a well, particularly an oil well, bymeasuring the velocity of the fluid ris- 55 ing within the well atvarious levels while maintaining substantially unrestricted fluid flowfrom all of the producing strata.

In using my apparatus the velocity of the fluid flowing up the well ismeasured by means of a suitable flowmeter which is continuously lowered6 in the well either throughout its entire depth or over the range whichit is desired to explore.

Flowmeters of a number of types may be used in accordance with myinvention, but they must of course be adapted to be lowered into aproduc- 10 ing well. My preferred form of flowmeter, however, utilizesthe Pitot tube principle and will be described in detail below inconnection with Figure 2. Regardless of the type employed, means arepreferably provided for electrically transmit- 16 ting an indication ofthe velocity of the fluid up the well from the level of the flowmeter tothe surface of the earth, where it can be recorded continuously in awell-known manner or read and recorded by an operator. I 20 Indetermining horizon productivity by the use of my apparatus, theflowmeter is continuously lowered into the well and, if the instrumentis of the remote-indicating type, observations are made'of fluidvelocity at various depths either by reading an indicator dial or bymaking a continuous record. When recording apparatus is used it ispreferred to move the recording tape in synchronism with the lowering ofthe flowmeter so that a direct plot of fluid velocity versus depth isobtained. If the instrument is of the self-contained recording type, arecord is kept of the time at which the flowmeter is at various depths,so that the velocity versus time chart made by the instrument may beutilized to yield information as to the fluid velocity at variousdepths.

' From the velocity data obtained the productive horizons are located bynoting the depths at which velocity increases are found when the well 40is of approximately uniform diameter. In order to evaluate the horizonproductivity at various levels, however, it is obvious that the welldiameters atthose levels must be taken into account, as can easily bedone by one skilled in the art of oil or gas production. It is notnecessary to calibrate the flowmeter to give direct indications of thevelocity of flow of fluids up the well, although this can be done,because the total production is always known, and the relativevelocities at various levels give sufiicient data to calculate theproductivities of the various horizons contributing to the production.

I can also operate by lowering the flowmeter to a giver. level,observing or recording the velocity at that level, lowering theflowmeter to another level, again determining the velocity, etc. By sooperating a number of the advantages of the invention are obtained. Thisvariation is particularly useful when the levels of the producing strataare known and it is desired to determine their productivities. A greatdeal of time is saved by making velocity measurements at levels justabove and just below each of these strata. Although I have hereinabovereferred to the lowering of the flowmeter, obviously the same resultscan be obtained by making velocity measurements during the upward travelof the fiowmeter, or the measurements can be made in both directions oftravel of the flowmeter and averaged to obtain more accurate values.

Referring now to Figure 1, which is a schematic representation of mypreferred apparatus, a producing well I is shown within which a suitableflowmeter II is suspended by means of a cable l2. Cable I2 passes arounda measuring spool I3 equipped with a revolution counter or similardevice (not shown) so that the depth of flowmeter II at any time can beread, and is supported by and wound upon drum I4, which is provided withwell-known means not shown for rotation in either direction so thatflowmeter II can be lowered or raised in well I8 as desired.

If flowmeter II is of the self-contained recording type, no otherapparatus is necessary, but in the embodiment shown, flowmeter I I is ofa type which contains means for transforming changes in velocity of thefluid up the well into electrical variations, so that two electricalconductors are incorporated in cable I2 for transmitting thesevariations to the top of the well which terminate at their upper ends inelectrical contact with slip rings I5 and I6 on drum I4. Brushes I1 andI8 contact rings I5 and I8 respectively and are connected electricallywith battery I9 and indicating device in series. When flowmeter IIcontains means for transforming changes in fluid velocity intoelectrical variations of a type which produces a variable electromotiveforce, battery I9 can be omitted and indicating device 28 can be anindicating or recording voltmeter or potentiometer.

Preferably, however, the device for translating flow variations intoelectrical variations is of a type which produces changes in the valueof a resistance responsive to variations in fluid flow, this resistancebeing incorporated in the circuit consisting of the conductors in cablel2, slip rings I5 and I6, brushes l1 and I8, battery I9 and indicatingdevice 20. In this case indicating device 20 is an indicating orrecording ammeter, and as shown is a recording ammeter having a pen arm2| and pen 22 so that a record of the electrical current flow is madeupon chart 23. Chart 23 is supplied by spool 24 and wound upon spool 25,which is actuated by a clock mechanism or, preferably, by a suitablemechanism connected to measuring spool I3, indicated schematically bydotted lines 26. The connecting mechanism for example can be entirelymechanical or can include the well-known Selsynmotors, but it must besuch that the rate of rotation of spool 25 is much lower than that ofmeasuring spool I3 and that the rates of rotation of the spools are inproportion to each other, so that a chart showing velocity of fluid flowversus depth of the externally threaded top cap 29, is providedimmediately above plug 28 with two downwardlyfacing Pitot tubes 30 andtwo upwardly-facing Pitot tubes 3| extending therethrough and arrangedso as to provide a pressure difierential due to the velocity of fluidsflowing outside but adjacent case 27 in a direction parallel to thelongitudinal axis thereof. The fit between Pitot tubes 38 and 3I andcase 21 is intentionally made quite loose so that no pressuredifferential can be built up between the outside and inside of case 21.A plurality of protecting fins 32 are aflixed to case 21 on either sideof Pitot tubes 30 and 3| so as to prevent injury to the Pitot tubes fromcontact with the sides of the well. Pitot tubes 30 lead to horizontaltube 33 within case 2'! having a vertical branch 34 communicating withan elongated reservoir 35, and Pitot tubes 3|, similarly communicatewith reservoir 38 by means of tube 36 and branch 37.

Immediately above reservoirs and 38 is a large tube 39, preferablyglass, having a small helical tube 40, preferably glass, surrounding itand communicating therewith at its lower end. Helical tube 48 contains acoil of resistance wire 4I (see Figure 4) throughout its length, theupper end of which is provided with a lead 42, and the lower end with alead 43 which passes up through tube 39 to its upper end and extendsbetween tube 39 and the rubber stopper 44 enclosing its upper end. Tubes39 and 48 are normally filled with a conducting liquid such as a brinesolution so that a portion of resistance coil 4| is short-circuited.Preferably resistance wire M is partially embedded in the glass of tubein order to prevent any movement thereof. This can be accomplished forexample by coiling the resistance wire around a metal rod, slipping aclose-fitting glass tube over the coil, flowing the glass around thewire by means of a blow torch, withdrawing the metal rod, and thenbending the glass tube into helical form.

Extending upwardly from the top of reservoir 35 between tube 39 andhelical tube 48 is positive pressure tube 45, which is attached byconnection 46 with one arm of inverted U-tube 41, the other arm of whichpasses through stopper 44. Similarly negative pressure tube 48 extendsupwardly from reservoir 38 and communicates with the upper end ofhelical tube 40. The purpose of reservoirs 35 and 38 is to provide ameans of preventing oil, dirt, etc. from entering tubes 39 and 40 andcontaminating the liquid therein.

The entire internal assembly is held in position by means of rubberpacking 48 between the two portions 49 and 50 of a split supportingmember 5| and the upper portion of tube 39. The portions 49 and 50 areheld together and made to grasp packing 48 firmly by means of screws 52(Figure 3), and the entire supporting member 5| is threaded on itscircumference so that it is held in position by means of internallythreaded portion 53 of case 21 and top cap 29. Supporting member 5| alsocarries an anchor 54 for'the suspension cable (not shown) which normallyis inserted through packing connection 55 in top cap 29. Two insulatedelectrical terminals 56 and 51 are provided in supporting member 5|,lead 42 being connected to the lower end of terminal 51 and lead 43 tothe upper end of terminal 56. By connecting the two electricalconductors contained in the suspension cable with terminals 56 and 51,resistance 4I is made available as a part of an electrical circuit asshown for instance in Figures 1 and 7.

The principle of operation pf my improved flowmeter may be more readilyunderstood from Figures 6 and 7 in which the various elements are giventhe same reference figures as corresponding parts of Figure 2.

From the above description it will be seen that the Pitot tubearrangement is of the combined reverse impact type which gives arelatively large pressure differential due to the velocity of the fluidflowing in the direction of the arrow on Figure 6. This pressuredifferential causes the level of the conducting liquid to rise in tube40 a distance responsive to the fluid velocity, thereby shortcir'cuiting a number of turns of the resistance coil M. The resistanceof coil 4| is therefore automatically varied in accordance with thevelocity of the fluid impinging on the Pitot tubes, and an indication ofthis fluid velocity can be obtained merely by measuring the value of theresistance between terminals 42 and 43.

This measurement is made by connecting coil 4i into a circuit as shownin Figure l with a battery i9 and an indicating device 2|], which can beof the indicating or recording type, as hereinabove described. A higherlevel of the conducting fluid in tube 40 will therefore reduce theresistance of coil 4i and cause a greater current to flow in thecircuit, which will of course be indicated or recorded by instrument 20.

Since battery l9 and instrument 2|! are located at the top of the welland my improved flowmeter is adapted to be lowered into a flowing well,the velocity of the fluid flowing up the well at any level or series ;oflevels therein can be determined readily.

While I have described my invention in connection with certain specificembodiments thereof, I do not desire to be limited thereto, but only 'bythe scope of the following claims.

I claim:

1. Apparatus for determining the horizon productivity in a producing oilor gas well which bomprises an elongated case, means for changing theelevation of said case within said well, means within said case forholding a supply of liquid, means responsive to the velocity of thefluid flow adjacent the exterior of said case parallel to thelongitudinal axis thereof for changing the level of said liquid, meansfor converting the changes in level of said liquid into electricalvariations, and means for transmitting said electrical variations to thetop of said well.

2. Apparatus for determining the horizon productivity in a producing oilor gas well which comprises an elongated case, means for changing theelevation of said case within said well, means within said case forholding a supply of liquid, means responsive to the velocity of thefluid flowing adjacent the exterior of said case parallel to thelongitudinal axis thereof for changing the level of said liquid, meansfor converting the changes in level of said liquid into electricalvariations, and means for recording said electrical variations.

3. Apparatus for determining the horizon productivity in a producing oilor gas well which comprises an elongated case, means for changing theelevation of said case within said well, means within said case forholding a supply of a liquid, means responsive to the velocityofthe-fluid flowing adjacent the exterior of said case parallel to thelongitudinal axis thereof for changing the level of said liquid, anelectrical resistance varying in response to changes in the level ofsaid liquid, means for supplying an electrical current to saidresistance, and means for measuring the resulting variations in thevalue of said electrical current.

4. An electric flowmeter for oil or gas wells which comprises anelongated case, a helical tube supported within said case, a liquidreservoir associated with said tube, a supply of a conducting liquidpartly filling said reservoir and said tube, means responsive 'to thevelocity of the fluid flowing adjacent the exterior of said casingparallel to the longitudinal axis thereof for changing the level of saidconducting liquid in said tube, an electrical resistance associated Iwith said helical tube in contact with said conducting liquid, means forpassing an electric current through said resistance, and means forindicating changes in said electric current.

5. An electric flowmeter according to claim 4 wherein said means forchanging the level of said conducting liquid includes a Pitot tube.

. WIIL S. SEASE.

